SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f40db2a886f0684733d157f873e18244e09582348954db39a9799ab4a035241c' 
  AND token = 'JRb0pl3lmTisK0kxp+tbGZzP1PD5ttUPQYjaFoftCzU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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