SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6165602259e88ddc5f151b95da0931368dadd3321b9b4455a1b59235402243ea' 
  AND token = 'KsrFVmq30/88dvSRP64w0RdzS0FzVRd0kwNNs+fa3qs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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