SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ef934021b4e03263446a98fbd9131bf211a9f69debde96256049d0e080c4f94a' 
  AND token = 'NXh9LlyxaEQxyDXpqLkGntPZe2TfUHpXMEHC9UQRxOQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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