SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c52cfe19701d102c84044e4f8834fcc175f1def3fd150f08cd01c2901d3b4912' 
  AND token = '9LJcfLoui/dt3n7vicejYxjIZevhpKBBX9Iw+4UgVkk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}