SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '91598629bfb5c047eb3e4c81d56f953adea01f140784ddd80e1460a7c3a6ac7e' 
  AND token = '1u3qrbcSbz2ASQ18pjP+idoRJdKEujPnSKVCkBVsUf8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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