SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8f5f46c443c13a077c482f132ea94d524840f520103357e882b9f3e636a609e8' 
  AND token = 'HtDh0xNLkVYU96L0JO7RAgBJ4O5QMvQo4CSjFiGpqs0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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