SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '92a4ff5d8f64ee99fa0e9087e371dd0eab80f846cee0dfdd320bfbb4c9cfe5ff' 
  AND token = 'wvOXJIX1JhEcph2FlQ3uLWwrOx+bhaNnc0VQzj4c2a8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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