SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '855797b0abd40f7dbbc23e5e59103624beace59c1c71f7a18f6ca64e197bd767' 
  AND token = 'lYzf/0nADBZbqZkdTf4jOpJUfHvkohmvBewbs3lEj/A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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