SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4d4b347f734739aa8e9236c6d8a5d10272fb124175bc951d51a86f321901d37e' 
  AND token = '/RnmYWOQ9csBKUdD0dVJt9weCr+EwwyxwCxnSvWw/uI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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