SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c2d71106a9771bb55f7dee13842f9f9d5279e0836bc3e2d7d943c1f54d6818ff' 
  AND token = 'gg9PMTtCFD20Wp/TwTWJBUrZhGxh5vyYyfFiicoDOkU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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