SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cf0841ba7c82d650493cd80f0f8fe0875c5ddead05f15043a55cbdd1b41eb3d1' 
  AND token = 'mc6LeIqvutKD2an860YMvw9l0Ohq4tTjVAq9Z4qhXJo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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