SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '340eb459d4caa4f24e943f3596dd6b23d1843a83937dd16bf07457b688e39fbf' 
  AND token = 'u8vbbobzJGrkglUVbKJ+QP+wWIRMXG7DcDfjxvuZM6U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00013

JSON explain

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