SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e5c3688b724f76289598b21a39017e9592431f745737ea80bcd93f26f26c51d8' 
  AND token = 'ToICEWONSK+SBa/DRwLb1TQRf+ZnDVtL7Q+4UcAwKGU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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