SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1404b81bd3b5786fb73f788afb093573507d1abc9f62c93dd375087bcf9cdafa' 
  AND token = '+gUlCD831tplI0QKDHGYUWVZheAIC+M3He8zZLM5ThY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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