SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '604be6a140226e4e9d8b8ab5f1f903c8b4025190dc2e0a4cd5b0b9dd4a86fe47' 
  AND token = 'Q+DTPj5ZowPA7mpk8pY/Frtz4g5JfkbxFYvgUliGjxY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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