SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '543fbc0fbe7768f27569815b8ffcdd35c8e326d23a6d2ac1fc236366323dffbb' 
  AND token = '36ndZfTCIiRAexWH3a9AKBG0aMfqGl7CpD5qpVkuiDs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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