SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '920816e5787538dcee68da0d4b4cbcbc2161a2b99925dafceed64128398e71d2' 
  AND token = 'KaHkj1GddyjwjbB0LtPl8PSCxnov7RLV28A6XtBjz7U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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