SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5fbc958b7b5b082d002be7ad86e9e864070dbd871a0245f1f61604721b34cce5' 
  AND token = 'dhMwZqxRBakZCy5mr9ibEJiSmPLl8Lx5IhPiBETKZ9g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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