SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '21a9bb1eb5dc812e88620c28166faa8801f91c60115f2ff5696f61749a4c9390' 
  AND token = 'h+Rp0EvBFkT3tsbZvLl0QfkLDDhVqlvXjgzU9OEW7pw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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