SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a5703dff99568d661daa225ab78981b9ed85a9d134fb125e9e28a7da925607e1' 
  AND token = 'UReCvu4rZ2TbQKItav/OtXj0jOzFyOrwGjZK1lSZ/+w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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