SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6bc72637b601f80abdbdbd67a3d7cdedededf189e3a084e49ed1db38f389bc63' 
  AND token = '94JpBAtyPuUrrA8kt0tjV4wKQpweaFdRjgih1AojI40=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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