SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9f75a9f16b0943831e439fe268f70f9004c238f44fd1f8e5ae8d7edc48c23ea7' 
  AND token = 'ASJbXKJriP+Yw1zMgSoZn8GYJSeFDKykGFANYRWyq78=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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