SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a8364ce0c05cc480a943bfffb3b713905fafee0501dcf03ac20d021daace5a2d' 
  AND token = 'dSg9ickpoZhXoDYD9V+wJvKvTZ+CWM/niz4OouByojs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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