SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '77848c21a06c39f56525d1300c04621390fd245c7bc856a877710201661c6d75' 
  AND token = 'SjRWWh22tYWOC8sgRYzqUr8cWUGejQae7kwzYZRnpqs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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