SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1927edc19bdcf7085102b420deacb35add4eb93c97684c685608803a78bd78ef' 
  AND token = 'OL9amqJUwKrvxw5Z3u+WjtM6jYOm7S+Y+Sh6blr6wXA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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