SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8d0f2501748cac83a57e32bec232704f37dc19ee9c929375e9f93bff5be4e94b' 
  AND token = 'f3UHMkDImzSbPz/f06OqjnNehjLGLOpptqjPVeYUMo8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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