SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'caadf0c46ecd86e512f48b21ee5fefe432ea1f70e393519bae2f2855a5f18d71' 
  AND token = '9KNvmqJi48WuQR1lfMLi0D+vGmBe1MATF86LTShxzgM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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