SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '24a5d8b12bf3534694ed931c5140999292cf9e94c48edbb027000652ce5eb351' 
  AND token = 'aIAJmfF2KRrTlsr5CEK5m/9+v8Mr+WYL0FtPTiiT6Kc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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