SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1b31c53415157fd56847e5c729106524fc8b68b752ef30f7291ce0b648bb6820' 
  AND token = 'wS4wj9CfcKiGbvclzNAD2b5FnmJhNYEgoesbSiZMWGY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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