SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd7957d9d89ee7297cb49d72f68410b79321946064a97cf8d88fd3d40d905a927' 
  AND token = '78jwoCfu2ErvXWo8w9layLs1ar6ULtYq38MMB9M1fkI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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