SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b70ed96f52a8ebfce27a1db375dee26c82397b5c867c9eeb336cb9fa45456d48' 
  AND token = '6vfoxg0AkjosbgTcGBXeGP8T6JhpTdIZzaCSuf96YH8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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