SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b778446f5bc3c27de72f09d4b13d4f57ce723116e8989782664a7c2994441298' 
  AND token = 'usyISxuTVsYugjjsxMGgXpUOW2r6oiwTCi5OzCS/AOQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

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