SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '644988c192ba1f74eccc833afe2c32889abf157dbe1f11fdc3fd9fa98fabd788' 
  AND token = '70mDmGmW1NjD3I2vH7/oZjRN9Ubi8/rm9BZ8FZuLFBY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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