SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e3a9c1515198b4cf21c438e108dd7e30ba8619470158780da9a52011c99fb05c' 
  AND token = 'MIAcXQ34W2/2xSrTrYNqZVdcQyRqGAfVPMJ6EB/cgpg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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