SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '811909e6579740a432942a18537de8d28b4dc90c504b18fd22180338b1172d50' 
  AND token = 'uRpJc84sOSx8m6GKyJDlV56KbLaBCg8V040Z2emHtm4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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