SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f8f033b864ed69ff6ef30ee90245b4ba5a31cf4ebe8b5eb0db921e9e062a2762' 
  AND token = 'mZHXKQF6LjqPuVpMdqTtOvN6/ToC1D+8iPyDO47Uiqw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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