SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2309b48dfd68ad27c6f5744fe5538ff90ddfe5f49efb5143ecb019d12fc98482' 
  AND token = 'Y3Ee7EqpdFjz0a5ovOUMPgjUYYNabXIMy7dKhRKp34s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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