SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e1db58dd5e98694ebe982bffe672df188deeada123abe7b67025374ececb503a' 
  AND token = '8RtWpmahGr0ktmWZlhH0N2/GNYdJ6BsIFe+NCybwBh4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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