SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c4f66f1c61f963a3a76784056c88bb5aa0ebf9d8b82eee5491aefb72b9218896' 
  AND token = 'zbpI+snyipL5RroxxjRJ2AdAdQnfQRMURrL3JEjMmrg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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