SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '50e53457941d06ddecfa3626c56ffc38b0e79a54ebf051e78ee715d2b73b3588' 
  AND token = '9yMDCmZhdXSu5aFk3u6y81pInAqOEcQReJdLYZe1bUk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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