SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1b1f9e9d2344cc236841817dc19f280dc8a5f332b30b1b98edfe10c29c845126' 
  AND token = 'c6RjCO0qw0HiRUXTnfgEvzMIen4H7VwuKHrmxpCk+NA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00045

JSON explain

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