SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'de50efe518baaf0e24b1c3d2300ebedc5d09327472e08a5b259026cc8648f54e' 
  AND token = 'wiQ6MTLxXzjJICFpurFrNItk8Zyn7U8AQVZB0U2z+tk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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