SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b8b67cab30ca64c8de4482bfd7c212f524eb76b4034c1bdaff156b4dba0c68b4' 
  AND token = 'VUZAZLY4BDEESqm4Sbf3Ph41jGAjqbGto10jqbdU0C0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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