SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd7bbcc98a29d63035c6d8f169c194da2ee5ca0aede186624eadedef8cbe94536' 
  AND token = '+vXtXO5VSW+H4hzjpKvOhQzSmcnVnkL3bTD4uaYGGt8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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