SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b31591e3fcd4d32e74b379dd42f1604f842eacb9621330a7438d78665057f276' 
  AND token = 'MLgIMDYftXNm6nrii3WIcTwFAAF2yELfTZMMeYfe/wA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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