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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3cbc2c3af99599ca1a95f3c5c19059536f7f364f84fadfcc52d3615bbe519541' 
  AND token = 'Y3Yx6n68NBZxV248SV7rHMktK6UCJoSSbP9OHLYUqaM=' 
  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"
    }
  }
}