SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '43e414f986af80de3f6add1c02b19f945492301c2030267f5020502d855c0fd9' 
  AND token = '3Dze6iby+urMJSIsrHbyrNA0fcBpvE4ONI3HjaNhtcs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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