SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '14fd1931d4fb268c51dc7b0e94654663adc7f808161ece968b8628e6263e7a5c' 
  AND token = '8PtQ5IPCGSJorv/Z+c5UKlWoXV0Sr3VV2RW9dAx7Bs4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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