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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b8413c33716fc213198d3a6ee6d21875630aa80f6c6a62c138c5254eb5f1b153' 
  AND token = 'NFx9scJjIMbL1zHkt7AMkQBEgqqfySk+uV4FTjpFF+o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00011

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}