SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f673fbc6a49f1512321ba31d805c243d061b3a1618a9a10582dcb582d1da879c' 
  AND token = 'ThNqhCVLedOWFflAf72bph/21OJbgUzUEbycjYqO2wo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00048

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}