SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '304e253f81695b73849da90658fa2efafc3b6a1f449f96406ec82123c6bcd03b' 
  AND token = 'NfFCqVEIdHXoFe2POgzwS+3YpMwZEg0ZnFZqAgvroYw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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