SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3a8da89754d0a5ea80b13260520313d2fc2bff4c720242558e65eb553a5e4171' 
  AND token = 'OoP8tlwtaa4yerARK4b/7QE/16TbRafg4D+pzlXiuzM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00053

JSON explain

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