SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b809035e2520047e047076a705e8edc43dee63a0bb039aba38a85d57418be9cc' 
  AND token = 'jFXJsRzqd6nkKsQqvmAGUQffkJiU55xgj+a+xxRgs9U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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