SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '76f2234ba78544b204117d847c1db28075179bef87167acffc1989c3bb2ec2c1' 
  AND token = 'PZ2zaaDv31BGocf7V0ayCS4nxVZOxdbaA/7eiiLc6H4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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