SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c4321a0081ae9f3e34c934db7c545f0acbebeb943a555e200e74e28fd1cbf105' 
  AND token = 'AlpHjYG3kLxykj/AvicckcGoCtLKfOGk68STifbsxuA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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