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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '51eb11a12c4f791bfb0687ca32092817783c5d8f2b42736fa2568af1f8c32c80' 
  AND token = 'GxHvcgJWage9xmk3k4FZguQQgcXGYjG3aMxhTFPw8tE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00012

JSON explain

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