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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9e8253ec1c9f3c81e9172a797322d53e51fe57fe9e35c97c8133752078f1d6f1' 
  AND token = '55fc372yoJSZPVSp7LJShEHuU30cvDVQcVmxTn5e++U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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