SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a2b832c89d115e6e937278491c004612931bc1eb50bde795d548fae776ce5a3f' 
  AND token = 'fm1dx1LGllaquAXFDBbHtJp7dPLrgDgH61Xv1VSTyUU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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