SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6e2a9411baf44cd7f54c1a7d6126b0f3081170d4554825fbd6fd5fc4650f8d48' 
  AND token = '0kUxtmEHFqBUR5m3eNCDLsPEf1pQU1Kxzu74aSeixPQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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