SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b10e3551802ad4f919901eaf7af8542488ec4ae8835a431ee09c9a48941ab9fa' 
  AND token = 's8L5SJtm/9gFKhdYPHHXScit+dYpydJEa/2bw0J/bl4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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