SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '156f06687603486eb1115300be528220c14bd17a0fda297ce92e9186e6060d5f' 
  AND token = 'KJUkiJc0vYqqMJZXP1Sk5rNgj+fD1IUnmqf3gKhKJfU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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