SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '17b38de32042017d8a745396a0b3f82d87ea514986e54bf57b43703ba9e9dc86' 
  AND token = 'UG86Ky46qWnplzGgzjwZMI99TTmUaAB/QWKAKWZMvOw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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