SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '574fbd8e53adcbe7bde4b2fb1fd183bca12f7a9018e42ccc9735e9dc516b4adf' 
  AND token = 'DsbXFwGpDZm6BtiZ9mddO/RsZ8MzjVPd/aOQwa/KwhE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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