SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '18cdbc1feed51b65149fba54ab3447f67f2e208bb3a4b7b5f3619acb9e53ed92' 
  AND token = 'l0tdKMQCd5jqimZpRQQ5VsnEsZvVNn+O1FwhOwcoZWg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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